Hotmail users can use the "name+something@hotmail.com" email filtering trick—so, you know, it's at Gmail's level from five years ago. But it's got an even more powerful spam-fighting, privacy-protecting option: creating an entirely new address that arrives right in your inbox.

Each Hotmail user gets five aliases per year, and a total of 15 aliases. The tricky part is finding email addresses that haven't been taken on the world's most popular email service, but if you can think up a long or unique enough thread, your Hotmail alias is really convenient. You hand it out, the email arrives into a labeled folder in your inbox, and you reply or forward those messages from that same address—or you can switch back to your regular email address when everything appears on the up-and-up.